Hello,

Class for sub-title: body .title-wrapper .title-subtitle class for title http://prntscr.com/m5dxjl

Tab label class is .woodmart-products-tabs.tabs-design-default .products-tabs-title .tab-label

Navigate to the Theme Settings > Typography > Advanced Typography and configure the styles as per your needs https://xtemos.com/docs/woodmart/advanced-typography-settings/

Best Regards